yamlSchemaService.ts

/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Red Hat, Inc. All rights reserved.
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

import {
  ISchemaContributions,
  JSONSchemaService,
  ResolvedSchema,
  SchemaDependencies,
  SchemaHandle,
  UnresolvedSchema,
} from 'vscode-json-languageservice/lib/umd/services/jsonSchemaService';
import { SettingsState } from '../../yamlSettings';
import { JSONSchema, JSONSchemaMap, JSONSchemaRef, SchemaDialect } from '../jsonSchema';
import { SchemaPriority, SchemaRequestService, WorkspaceContextService } from '../yamlLanguageService';

import * as l10n from '@vscode/l10n';
import * as path from 'path';
import { URI } from 'vscode-uri';
import { JSONSchemaDescriptionExt } from '../../requestTypes';
import { JSONDocument } from '../parser/jsonDocument';
import { SingleYAMLDocument } from '../parser/yamlParser07';
import { SchemaVersions } from '../yamlTypes';
import { getSchemaFromModeline } from './modelineUtil';

import Ajv, { DefinedError, type AnySchemaObject, type ValidateFunction } from 'ajv';
import Ajv4 from 'ajv-draft-04';
import Ajv2019 from 'ajv/dist/2019';
import Ajv2020 from 'ajv/dist/2020';
import * as Json from 'jsonc-parser';
import { parse } from 'yaml';
import { CRD_CATALOG_URL, KUBERNETES_SCHEMA_URL } from '../utils/schemaUrls';
import { autoDetectKubernetesSchema } from './k8sSchemaUtil';

const ajv4 = new Ajv4({ allErrors: true });
const ajv7 = new Ajv({ allErrors: true });
const ajv2019 = new Ajv2019({ allErrors: true });
const ajv2020 = new Ajv2020({ allErrors: true });

// eslint-disable-next-line @typescript-eslint/no-var-requires
const jsonSchema04 = require('ajv-draft-04/dist/refs/json-schema-draft-04.json');
// eslint-disable-next-line @typescript-eslint/no-var-requires
const jsonSchema07 = require('ajv/dist/refs/json-schema-draft-07.json');
// eslint-disable-next-line @typescript-eslint/no-var-requires
const jsonSchema2019 = require('ajv/dist/refs/json-schema-2019-09/schema.json');
// eslint-disable-next-line @typescript-eslint/no-var-requires
const jsonSchema2020 = require('ajv/dist/refs/json-schema-2020-12/schema.json');

const schema04Validator = ajv4.compile(jsonSchema04);
const schema07Validator = ajv7.compile(jsonSchema07);
const schema2019Validator = ajv2019.compile(jsonSchema2019);
const schema2020Validator = ajv2020.compile(jsonSchema2020);

const schemaDialectCache = new Map<string, SchemaDialect>();
const schemaDialectInFlight = new Map<string, Promise<SchemaDialect>>();

// metadata/keywords that don't add constraints and thus don't count as $ref siblings
const REF_SIBLING_NONCONSTRAINT_KEYS = new Set([
  '$ref',
  '_$ref',
  '$schema',
  '$id',
  'id',
  '_baseUrl',
  '_dialect',
  '$anchor',
  '$dynamicAnchor',
  '$dynamicRef',
  '$recursiveAnchor',
  '$recursiveRef',
  'definitions',
  '$defs',
  '$comment',
  'title',
  'description',
  'markdownDescription',
  '$vocabulary',
  'examples',
  'default',
  'url',
  'closestTitle',
  'unevaluatedProperties',
  'unevaluatedItems',
]);

export declare type CustomSchemaProvider = (uri: string) => Promise<string | string[]>;

export enum MODIFICATION_ACTIONS {
  'delete',
  'add',
  'deleteAll',
}

export interface SchemaAdditions {
  schema: string;
  action: MODIFICATION_ACTIONS.add;
  path: string;
  key: string;
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  content: any;
}

export interface SchemaDeletions {
  schema: string;
  action: MODIFICATION_ACTIONS.delete;
  path: string;
  key: string;
}

export interface SchemaDeletionsAll {
  schemas: string[];
  action: MODIFICATION_ACTIONS.deleteAll;
}

interface SchemaStoreSchema {
  name: string;
  description: string;
  versions?: SchemaVersions;
}
export class YAMLSchemaService extends JSONSchemaService {
  // To allow to use schemasById from super.
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  [x: string]: any;

  private customSchemaProvider: CustomSchemaProvider | undefined;
  private filePatternAssociations: JSONSchemaService.FilePatternAssociation[];
  private contextService: WorkspaceContextService;
  private requestService: SchemaRequestService;
  private yamlSettings: SettingsState;
  public schemaPriorityMapping: Map<string, Set<SchemaPriority>>;

  private schemaUriToNameAndDescription = new Map<string, SchemaStoreSchema>();

  constructor(
    requestService: SchemaRequestService,
    contextService?: WorkspaceContextService,
    promiseConstructor?: PromiseConstructor,
    yamlSettings?: SettingsState
  ) {
    super(requestService, contextService, promiseConstructor);
    this.customSchemaProvider = undefined;
    this.requestService = requestService;
    this.schemaPriorityMapping = new Map();
    this.yamlSettings = yamlSettings;
  }

  registerCustomSchemaProvider(customSchemaProvider: CustomSchemaProvider): void {
    this.customSchemaProvider = customSchemaProvider;
  }

  getAllSchemas(): JSONSchemaDescriptionExt[] {
    const result: JSONSchemaDescriptionExt[] = [];
    const schemaUris = new Set<string>();
    for (const filePattern of this.filePatternAssociations) {
      const schemaUri = filePattern.uris[0];
      if (schemaUris.has(schemaUri)) {
        continue;
      }
      schemaUris.add(schemaUri);
      const schemaHandle: JSONSchemaDescriptionExt = {
        uri: schemaUri,
        fromStore: false,
        usedForCurrentFile: false,
      };

      if (this.schemaUriToNameAndDescription.has(schemaUri)) {
        const { name, description, versions } = this.schemaUriToNameAndDescription.get(schemaUri);
        schemaHandle.name = name;
        schemaHandle.description = description;
        schemaHandle.fromStore = true;
        schemaHandle.versions = versions;
      }
      result.push(schemaHandle);
    }

    return result;
  }

  private collectSchemaNodes(push: (node: JSONSchema) => void, ...values: unknown[]): void {
    const collect = (value: unknown): void => {
      if (!value || typeof value !== 'object') return;
      if (Array.isArray(value)) {
        for (const entry of value) {
          collect(entry);
        }
        return;
      }
      push(value as JSONSchema);
    };
    for (const value of values) {
      collect(value);
    }
  }

  private schemaMapValues(map?: JSONSchemaMap): JSONSchemaRef[] | undefined {
    if (!map || typeof map !== 'object') return undefined;
    return Object.values(map);
  }

  async resolveSchemaContent(
    schemaToResolve: UnresolvedSchema,
    schemaURL: string,
    dependencies: SchemaDependencies
  ): Promise<ResolvedSchema> {
    const resolveErrors: string[] = schemaToResolve.errors.slice(0);
    const loc = toDisplayString(schemaURL);

    const raw: unknown = schemaToResolve.schema;
    if (raw === null || Array.isArray(raw) || (typeof raw !== 'object' && typeof raw !== 'boolean')) {
      const got = raw === null ? 'null' : Array.isArray(raw) ? 'array' : typeof raw;
      resolveErrors.push(
        l10n.t("Schema '{0}' is not valid: {1}", loc, `expected a JSON Schema object or boolean, got "${got}".`)
      );
      return new ResolvedSchema({}, resolveErrors);
    }

    const _cloneSchema = (
      value: unknown,
      seen: Map<object, unknown>,
      stopCondition?: (val: unknown, seenSize: number) => unknown | undefined
    ): unknown => {
      // primitives and null
      if (value === null || typeof value !== 'object') return value;

      if (stopCondition) {
        const replacement = stopCondition(value, seen.size);
        if (replacement !== undefined) return replacement;
      }

      // already cloned
      if (seen.has(value)) return seen.get(value);

      // clone arrays
      if (Array.isArray(value)) {
        const arr = [];
        seen.set(value, arr);
        for (const item of value) {
          arr.push(_cloneSchema(item, seen, stopCondition));
        }
        return arr;
      }

      // clone objects
      const result = {};
      seen.set(value, result);
      for (const prop in value) {
        result[prop] = _cloneSchema(value[prop], seen, stopCondition);
      }
      return result;
    };

    /**
     * ----------------------------
     * Meta-validate a schema node against its dialect's meta-schema
     * ----------------------------
     */
    const _loadSchema = this.loadSchema.bind(this);
    async function _metaValidateSchemaNode(node: JSONSchema, hasNestedSchema: boolean): Promise<void> {
      if (!node || typeof node !== 'object') return;
      const dialect = await pickSchemaDialect(node.$schema, _loadSchema);
      dialect && (node._dialect = dialect);

      const validator = pickMetaValidator(dialect);
      if (!validator) return;

      let toValidate = node;
      if (hasNestedSchema) {
        // clone for meta-validation: stop at dialect boundaries abd replace with {}
        const stopAtDialectBoundary = (val: JSONSchema, seenSize: number): JSONSchema | undefined => {
          if (seenSize !== 0 && val && typeof val === 'object' && val.$schema) return {};
          return undefined;
        };
        toValidate = _cloneSchema(node, new Map(), stopAtDialectBoundary) as JSONSchema;
      }

      if (!validator(toValidate)) {
        const errs: string[] = [];
        for (const err of validator.errors as DefinedError[]) {
          errs.push(`${err.instancePath} : ${err.message}`);
        }
        resolveErrors.push(l10n.t("Schema '{0}' is not valid: {1}", loc, `\n${errs.join('\n')}`));
      }
    }

    /**
     * ----------------------------
     * Schema resource and fragment resolution
     * ----------------------------
     * Manages two types of schema identification:
     * 1. Embedded resources ($id without fragment):
     *    Creates a new resource scope that can be referenced by other schemas, e.g. "$id": "other.json"
     * 2. Plain-name fragments/anchors:
     *    Creates named anchors within a resource for direct reference.
     *
     * Cache per resource URI in resourceIndexByUri:
     * - root: schema node for the resource
     * - fragments: map of plain-name anchors to their schema nodes + dynamic flag
     */
    type FragmentEntry = { node: JSONSchema; dynamic?: boolean };
    type PlainNameFragmentMap = Map<string, FragmentEntry>;
    type ResourceIndex = { root?: JSONSchema; fragments: PlainNameFragmentMap };
    const resourceIndexByUri = new Map<string, ResourceIndex>();

    const _getResourceIndex = (resourceUri: string): ResourceIndex => {
      let entry = resourceIndexByUri.get(resourceUri);
      if (!entry) {
        entry = { fragments: new Map<string, FragmentEntry>() };
        resourceIndexByUri.set(resourceUri, entry);
      }
      return entry;
    };

    /**
     * Adds a resource's dynamic anchors to the inherited scope from parent resources
     *
     * Draft 2020-12: For $dynamicRef resolution, when schema A references schema B,
     * B's dynamic anchors are added to A's scope. This builds a chain where $dynamicRef
     * looks for the outermost (first) matching anchor.
     */
    const _addResourceDynamicAnchors = (
      scope: Map<string, JSONSchema[]> | undefined,
      resourceUri: string | undefined
    ): Map<string, JSONSchema[]> | undefined => {
      const entry = resourceIndexByUri.get(resourceUri);
      if (!entry || entry.fragments.size === 0) return scope;

      let result = scope;
      for (const [name, entryItem] of entry.fragments) {
        if (!entryItem.dynamic) continue;

        const current = result?.get(name) ?? [];
        if (current.some((existing) => existing._baseUrl === resourceUri)) continue;

        // clone map on first modification
        if (result === scope) result = scope ? new Map(scope) : new Map<string, JSONSchema[]>();
        result.set(name, current.concat(entryItem.node));
      }
      return result;
    };

    // resolve relative URI against base URI
    // e.g. resolve "./foo.json" against "http://example.com/bar.json" => "http://example.com/foo.json"
    const _resolveAgainstBase = (baseUri: string, ref: string): string => {
      if (this.contextService) return this.contextService.resolveRelativePath(ref, baseUri);
      return this.normalizeId(ref);
    };

    const _preferLocalBaseForRemoteId = async (currentBase: string, id: string): Promise<string> => {
      try {
        const currentBaseUri = URI.parse(currentBase);
        const idUri = URI.parse(id);
        const localFileName = path.posix.basename(idUri.path);
        const localDir = path.posix.dirname(currentBaseUri.path);
        const localPath = path.posix.join(localDir, localFileName);
        const localUriStr = currentBaseUri.with({ path: localPath, query: idUri.query, fragment: idUri.fragment }).toString();
        if (localUriStr === currentBase) return localUriStr;
        const content = await this.requestService(localUriStr);
        return content ? localUriStr : _resolveAgainstBase(currentBase, id);
      } catch {
        return _resolveAgainstBase(currentBase, id);
      }
    };

    const _indexSchemaResources = async (root: JSONSchema, initialBaseUri: string): Promise<void> => {
      type WorkItem = { node: JSONSchema; baseUri: string };
      const preOrderStack: WorkItem[] = [{ node: root, baseUri: initialBaseUri }];
      const postOrderStack: JSONSchema[] = [];
      const childListByNode = new WeakMap<JSONSchema, JSONSchema[]>();

      const seen = new Set<JSONSchema>();
      while (preOrderStack.length) {
        const current = preOrderStack.pop();
        if (!current) continue;

        const node = current.node;
        if (!node || typeof node !== 'object' || seen.has(node)) continue;
        seen.add(node);

        let baseUri = current.baseUri;
        const id = node.$id || node.id;
        if (id) {
          const preferredBaseUri = await _preferLocalBaseForRemoteId(baseUri, id);
          node._baseUrl = preferredBaseUri;
          const hashIndex = preferredBaseUri.indexOf('#');
          if (hashIndex !== -1 && hashIndex < preferredBaseUri.length - 1) {
            // Draft-07 and earlier: $id with fragment defines a plain-name anchor scoped to the resolved base
            const frag = preferredBaseUri.slice(hashIndex + 1);
            _getResourceIndex(baseUri).fragments.set(frag, { node });
          } else {
            // $id without fragment creates a new embedded resource scope
            baseUri = preferredBaseUri;
            const entry = _getResourceIndex(preferredBaseUri);
            if (!entry.root) {
              entry.root = node;
            }
          }
        }
        // Draft 2019-09+: $anchor keyword
        if (node.$anchor) {
          _getResourceIndex(baseUri).fragments.set(node.$anchor, { node });
        }
        // Draft 2020-12+: $dynamicAnchor keyword
        if (node.$dynamicAnchor) {
          node._baseUrl = baseUri;
          _getResourceIndex(baseUri).fragments.set(node.$dynamicAnchor, { node, dynamic: true });
        }

        const children: JSONSchema[] = [];
        childListByNode.set(node, children);

        // collect all child schemas
        this.collectSchemaNodes(
          (entry) => {
            children.push(entry);
            preOrderStack.push({ node: entry, baseUri });
          },
          node.not,
          node.if,
          node.then,
          node.else,
          node.contains,
          node.propertyNames,
          node.additionalProperties as JSONSchema,
          node.items,
          node.additionalItems,
          node.prefixItems,
          this.schemaMapValues(node.properties),
          this.schemaMapValues(node.patternProperties),
          this.schemaMapValues(node.definitions),
          this.schemaMapValues(node.$defs),
          this.schemaMapValues(node.dependentSchemas),
          this.schemaMapValues(node.dependencies as JSONSchemaMap),
          node.allOf,
          node.anyOf,
          node.oneOf,
          node.schemaSequence
        );
        postOrderStack.push(node);
      }

      const hasNestedSchema = new WeakMap<JSONSchema, boolean>();
      while (postOrderStack.length) {
        const node = postOrderStack.pop();
        let hasNested = false;
        for (const child of childListByNode.get(node)) {
          if (child.$schema || hasNestedSchema.get(child)) {
            hasNested = true;
            break;
          }
        }
        hasNestedSchema.set(node, hasNested);

        if (node === root || node.$schema) await _metaValidateSchemaNode(node, hasNested);
      }
    };

    let schema = raw as JSONSchema;
    const schemaBaseURL = schemaToResolve.uri ?? schemaURL;
    await _indexSchemaResources(schema, schemaBaseURL);

    const _findSection = (schemaRoot: JSONSchema, refPath: string, sourceURI: string): JSONSchema => {
      if (!refPath) {
        return schemaRoot;
      }

      // JSON pointer style
      if (refPath[0] === '/') {
        let current = schemaRoot;
        const parts = refPath.substr(1).split('/');
        for (const part of parts) {
          // in JSON Pointer: ~ must be escaped as ~0, / must be escaped as ~1
          current = current?.[part.replace(/~1/g, '/').replace(/~0/g, '~')];
          if (current === null) return undefined;
        }
        return current as JSONSchema;
      }

      // plain-name fragment ($anchor or $id#fragment) -> lookup in collected fragments
      return _getResourceIndex(sourceURI).fragments.get(refPath).node;
    };

    const _merge = (target: JSONSchema, sourceRoot: JSONSchema, sourceURI: string, refPath: string, clone = false): void => {
      const section = _findSection(sourceRoot, refPath, sourceURI);
      if (typeof section === 'boolean') {
        if (!section) target.not = {};
        return;
      }
      if (typeof section === 'object' && section) {
        const source = clone ? (_cloneSchema(section, new Map()) as JSONSchema) : section;
        for (const key in source) {
          if (Object.prototype.hasOwnProperty.call(source, key) && !Object.prototype.hasOwnProperty.call(target, key)) {
            target[key] = source[key];
          }
        }
        return;
      } else {
        resolveErrors.push(l10n.t("$ref '{0}' in '{1}' cannot be resolved.", refPath, sourceURI));
      }
    };

    const _resolveRefUri = (parentSchemaURL: string, refUri: string): string => {
      const resolvedAgainstParent = _resolveAgainstBase(parentSchemaURL, refUri);
      if (!refUri.startsWith('/')) return resolvedAgainstParent;
      const parentResource = resourceIndexByUri.get(parentSchemaURL)?.root;
      const parentResourceId = parentResource?.$id || parentResource?.id;
      const resolvedParentId = _resolveAgainstBase(parentSchemaURL, parentResourceId);
      if (!resolvedParentId.startsWith('http://') && !resolvedParentId.startsWith('https://')) return resolvedAgainstParent;

      return _resolveAgainstBase(resolvedParentId, refUri);
    };

    const _resolveLocalSiblingFromRemoteUri = (parentSchemaURL: string, resolvedRefUri: string): string | undefined => {
      try {
        const parentUri = URI.parse(parentSchemaURL);
        const targetUri = URI.parse(resolvedRefUri);
        if (parentUri.scheme !== 'file') return undefined;
        if (targetUri.scheme !== 'http' && targetUri.scheme !== 'https') return undefined;

        const localFileName = path.posix.basename(targetUri.path);
        if (!localFileName) return undefined;
        const localDir = path.posix.dirname(parentUri.path);
        const localPath = path.posix.join(localDir, localFileName);
        return parentUri.with({ path: localPath, query: targetUri.query, fragment: targetUri.fragment }).toString();
      } catch {
        return undefined;
      }
    };

    const resolveExternalLink = (
      node: JSONSchema,
      uri: string,
      linkPath: string,
      parentSchemaURL: string,
      parentSchemaDependencies: SchemaDependencies,
      resolutionStack: Set<string>,
      recursiveAnchorBase: string,
      inheritedDynamicScope: Map<string, JSONSchema[]>
      // eslint-disable-next-line @typescript-eslint/no-explicit-any
    ): Promise<any> => {
      const _attachResolvedSchema = (
        node: JSONSchema,
        schemaRoot: JSONSchema,
        schemaUri: string,
        linkPath: string,
        parentSchemaDependencies: SchemaDependencies,
        resolveRefDependencies: SchemaDependencies,
        resolutionStack: Set<string>,
        recursiveAnchorBase: string,
        inheritedDynamicScope: Map<string, JSONSchema[]>
        // eslint-disable-next-line @typescript-eslint/no-explicit-any
      ): Promise<any> => {
        parentSchemaDependencies[schemaUri] = true;
        _merge(node, schemaRoot, schemaUri, linkPath, !!inheritedDynamicScope || !!recursiveAnchorBase);
        if (!recursiveAnchorBase || !node._baseUrl) node._baseUrl = schemaUri;
        node.url = schemaUri;

        const nextStack = new Set(resolutionStack);
        nextStack.add(schemaUri);
        // eslint-disable-next-line @typescript-eslint/no-use-before-define
        return resolveRefs(
          node,
          schemaRoot,
          schemaUri,
          resolveRefDependencies,
          nextStack,
          recursiveAnchorBase,
          inheritedDynamicScope
        );
      };

      const _resolveByUri = (targetUris: string[], index = 0): Promise<unknown> => {
        const targetUri = targetUris[index];

        const embeddedSchema = resourceIndexByUri.get(targetUri)?.root;
        if (embeddedSchema) {
          return _attachResolvedSchema(
            node,
            embeddedSchema,
            targetUri,
            linkPath,
            parentSchemaDependencies,
            parentSchemaDependencies,
            resolutionStack,
            recursiveAnchorBase,
            inheritedDynamicScope
          );
        }

        const referencedHandle = this.getOrAddSchemaHandle(targetUri);
        return referencedHandle.getUnresolvedSchema().then(async (unresolvedSchema) => {
          if (
            unresolvedSchema.errors?.some((error) => error.toLowerCase().includes('unable to load schema from')) &&
            index + 1 < targetUris.length
          ) {
            return _resolveByUri(targetUris, index + 1);
          }

          if (unresolvedSchema.errors.length) {
            const loc = linkPath ? targetUri + '#' + linkPath : targetUri;
            resolveErrors.push(l10n.t("Problems loading reference '{0}': {1}", loc, unresolvedSchema.errors[0]));
          }
          // index resources for the newly loaded schema
          await _indexSchemaResources(unresolvedSchema.schema, targetUri);
          return _attachResolvedSchema(
            node,
            unresolvedSchema.schema,
            targetUri,
            linkPath,
            parentSchemaDependencies,
            referencedHandle.dependencies,
            resolutionStack,
            recursiveAnchorBase,
            inheritedDynamicScope
          );
        });
      };

      const resolvedUri = _resolveRefUri(parentSchemaURL, uri);
      const localSiblingUri = _resolveLocalSiblingFromRemoteUri(parentSchemaURL, resolvedUri);
      const targetUris = localSiblingUri && localSiblingUri !== resolvedUri ? [localSiblingUri, resolvedUri] : [resolvedUri];
      return _resolveByUri(targetUris);
    };

    const resolveRefs = async (
      node: JSONSchema,
      parentSchema: JSONSchema,
      parentSchemaURL: string,
      parentSchemaDependencies: SchemaDependencies,
      resolutionStack: Set<string>,
      recursiveAnchorBase?: string,
      inheritedDynamicScope?: Map<string, JSONSchema[]>
      // eslint-disable-next-line @typescript-eslint/no-explicit-any
    ): Promise<any> => {
      if (!node || typeof node !== 'object') {
        return null;
      }

      // track nodes with their base URL for $id resolution
      type WalkItem = {
        node: JSONSchema;
        baseURL?: string;
        dialect?: SchemaDialect;
        recursiveAnchorBase?: string;
        inheritedDynamicScope?: Map<string, JSONSchema[]>;
        siblingRefCycleKeys?: Set<string>;
      };
      const toWalk: WalkItem[] = [{ node, baseURL: parentSchemaURL, recursiveAnchorBase, inheritedDynamicScope }];
      const seen = new WeakSet<JSONSchema>(); // prevents re-walking the same schema object graph

      // eslint-disable-next-line @typescript-eslint/no-explicit-any
      const openPromises: Promise<any>[] = [];

      // handle $ref with siblings based on dialect
      const _handleRef = (
        next: JSONSchema,
        nodeBaseURL: string,
        nodeDialect: SchemaDialect,
        recursiveAnchorBase?: string,
        inheritedDynamicScope?: Map<string, JSONSchema[]>,
        siblingRefCycleKeys?: Set<string>
      ): void => {
        const currentDynamicScope = _addResourceDynamicAnchors(inheritedDynamicScope, nodeBaseURL);

        this.collectSchemaNodes(
          (entry) =>
            toWalk.push({ node: entry, baseURL: nodeBaseURL, recursiveAnchorBase, inheritedDynamicScope: currentDynamicScope }),
          this.schemaMapValues(next.definitions || next.$defs)
        );

        // checks if a node with $ref has other constraint keywords
        const _hasRefSiblings = (node: JSONSchema): boolean => {
          for (const k of Object.keys(node)) {
            if (REF_SIBLING_NONCONSTRAINT_KEYS.has(k)) continue;
            return true;
          }
          return false;
        };

        /**
         * For Draft-2019+:
         *   { $ref: "...", <siblings...> }
         * becomes
         *   { allOf: [ { $ref: "..." }, <siblings...> ] }
         */
        const _rewriteRefWithSiblingsToAllOf = (node: JSONSchema): void => {
          const siblings: JSONSchema = {};
          for (const k of Object.keys(node)) {
            if (!REF_SIBLING_NONCONSTRAINT_KEYS.has(k)) {
              siblings[k] = node[k];
              delete node[k];
            }
          }

          const refValue = node.$dynamicRef ?? node.$recursiveRef ?? node.$ref;
          if (typeof refValue !== 'string') return;
          node.allOf = [
            { [node.$dynamicRef ? '$dynamicRef' : node.$recursiveRef ? '$recursiveRef' : '$ref']: refValue } as JSONSchema,
            siblings,
          ];
          delete node.$dynamicRef;
          delete node.$recursiveRef;
          delete node.$ref;
        };

        const _stripRefSiblings = (node: JSONSchema): void => {
          for (const k of Object.keys(node)) {
            if (!REF_SIBLING_NONCONSTRAINT_KEYS.has(k)) delete node[k];
          }
        };

        const seenRefs = new Set<string>();

        const _mergeIfResourceAlreadyInResolutionStack = (ref: string, resolvedResource: string, frag: string): boolean => {
          if (!resolutionStack.has(resolvedResource)) return false;
          if (!seenRefs.has(ref)) {
            const source = resourceIndexByUri.get(resolvedResource)?.root;
            if (source && typeof source === 'object') {
              _merge(next, source, resolvedResource, frag, !!recursiveAnchorBase);
            }
            seenRefs.add(ref);
          }
          return true;
        };

        while (next.$dynamicRef || next.$recursiveRef || next.$ref) {
          const isDynamicRef = typeof next.$dynamicRef === 'string';
          const isRecursiveRef = !isDynamicRef && typeof next.$recursiveRef === 'string';
          const rawRef = next.$dynamicRef ?? next.$recursiveRef ?? next.$ref;
          if (typeof rawRef !== 'string') break;
          next._$ref = rawRef;

          // parse ref into base URI and fragment
          const ref = decodeURIComponent(rawRef);
          const segments = ref.split('#', 2);
          const baseUri = segments[0];
          const frag = segments.length > 1 ? segments[1] : '';
          const resolvedRefKey = `${baseUri ? _resolveAgainstBase(nodeBaseURL, baseUri) : nodeBaseURL}#${frag}`;

          if (_hasRefSiblings(next)) {
            // Draft-07 and earlier: ignore siblings
            if (nodeDialect === SchemaDialect.draft04 || nodeDialect === SchemaDialect.draft07) {
              _stripRefSiblings(next);
            } else {
              if (siblingRefCycleKeys?.has(resolvedRefKey)) break;

              // Draft-2019+: support sibling keywords
              _rewriteRefWithSiblingsToAllOf(next);
              if (Array.isArray(next.allOf)) {
                for (let i = 0; i < next.allOf.length; i++) {
                  const entry = next.allOf[i];
                  if (entry && typeof entry === 'object') {
                    let nextSiblingRefCycleKeys: Set<string> | undefined;
                    if (i === 0) {
                      nextSiblingRefCycleKeys = new Set(siblingRefCycleKeys);
                      nextSiblingRefCycleKeys.add(resolvedRefKey);
                    }
                    toWalk.push({
                      node: entry as JSONSchema,
                      baseURL: nodeBaseURL,
                      recursiveAnchorBase,
                      inheritedDynamicScope: currentDynamicScope,
                      siblingRefCycleKeys: nextSiblingRefCycleKeys,
                    });
                  }
                }
              }
              return;
            }
          }

          delete next.$dynamicRef;
          delete next.$recursiveRef;
          delete next.$ref;

          // Draft-2019+: $recursiveRef
          if (isRecursiveRef && (ref === '#' || ref === '')) {
            const targetRoot = resourceIndexByUri.get(nodeBaseURL)?.root;
            const recursiveBase = targetRoot?.$recursiveAnchor && recursiveAnchorBase ? recursiveAnchorBase : nodeBaseURL;

            if (recursiveBase.length > 0) {
              if (resolutionStack?.has(recursiveBase) || recursiveBase === nodeBaseURL) {
                const sourceRoot = resourceIndexByUri.get(recursiveBase)?.root ?? parentSchema;
                if (!seenRefs.has(ref)) {
                  _merge(next, sourceRoot, recursiveBase, '', false);
                  seenRefs.add(ref);
                }
                continue;
              }
              openPromises.push(
                resolveExternalLink(
                  next,
                  recursiveBase,
                  '',
                  nodeBaseURL,
                  parentSchemaDependencies,
                  resolutionStack,
                  recursiveAnchorBase,
                  currentDynamicScope
                )
              );
              return;
            }
            continue;
          }

          // Draft-2020+: $dynamicRef
          else if (isDynamicRef) {
            const targetResource = baseUri.length > 0 ? _resolveAgainstBase(nodeBaseURL, baseUri) : nodeBaseURL;
            const targetFragments = resourceIndexByUri.get(targetResource)?.fragments;
            const targetHasDynamicAnchor = frag.length > 0 && targetFragments?.get(frag)?.dynamic;
            const dynamicTarget = targetHasDynamicAnchor ? currentDynamicScope?.get(frag)?.[0] : undefined;
            const resolveResource = dynamicTarget ? dynamicTarget._baseUrl : targetResource;

            if (dynamicTarget && (resolveResource === nodeBaseURL || resolutionStack.has(resolveResource))) {
              if (!seenRefs.has(ref)) {
                _merge(next, dynamicTarget, resolveResource, '', false);
                seenRefs.add(ref);
              }
              continue;
            }

            if (baseUri.length > 0 || targetHasDynamicAnchor) {
              if (_mergeIfResourceAlreadyInResolutionStack(ref, resolveResource, frag)) continue;
              openPromises.push(
                resolveExternalLink(
                  next,
                  resolveResource,
                  frag,
                  nodeBaseURL,
                  parentSchemaDependencies,
                  resolutionStack,
                  recursiveAnchorBase,
                  currentDynamicScope
                )
              );
              return;
            }
          }
          // normal $ref with external baseUri
          else if (baseUri.length > 0) {
            const resolvedBaseUri = _resolveAgainstBase(nodeBaseURL, baseUri);
            if (_mergeIfResourceAlreadyInResolutionStack(ref, resolvedBaseUri, frag)) continue;
            // resolve relative to this node's base URL
            openPromises.push(
              resolveExternalLink(
                next,
                baseUri,
                frag,
                nodeBaseURL,
                parentSchemaDependencies,
                resolutionStack,
                recursiveAnchorBase,
                currentDynamicScope
              )
            );
            return;
          }

          // local $ref or $dynamicRef
          if (!seenRefs.has(ref)) {
            _merge(next, parentSchema, nodeBaseURL, frag, isDynamicRef && !!currentDynamicScope);
            seenRefs.add(ref);
          }
        }

        // recursively process children
        this.collectSchemaNodes(
          (entry) =>
            toWalk.push({
              node: entry,
              baseURL: next._baseUrl || nodeBaseURL,
              dialect: nodeDialect,
              recursiveAnchorBase,
              inheritedDynamicScope: currentDynamicScope,
            }),
          next.not,
          next.if,
          next.then,
          next.else,
          next.contains,
          next.propertyNames,
          next.additionalProperties as JSONSchema,
          next.items,
          next.additionalItems,
          next.prefixItems,
          this.schemaMapValues(next.properties),
          this.schemaMapValues(next.patternProperties),
          this.schemaMapValues(next.dependentSchemas),
          this.schemaMapValues(next.dependencies as JSONSchemaMap),
          next.allOf,
          next.anyOf,
          next.oneOf,
          next.schemaSequence
        );
      };

      // handle file path with fragments
      if (parentSchemaURL.indexOf('#') > 0) {
        const segments = parentSchemaURL.split('#', 2);
        if (segments[0].length > 0 && segments[1].length > 0) {
          const newSchema = {};
          await resolveExternalLink(
            newSchema,
            segments[0],
            segments[1],
            parentSchemaURL,
            parentSchemaDependencies,
            resolutionStack,
            recursiveAnchorBase,
            inheritedDynamicScope
          );
          for (const key in schema) {
            if (key === 'required') {
              continue;
            }
            if (Object.prototype.hasOwnProperty.call(schema, key) && !Object.prototype.hasOwnProperty.call(newSchema, key)) {
              newSchema[key] = schema[key];
            }
          }
          schema = newSchema;
        }
      }

      while (toWalk.length) {
        const item = toWalk.pop();
        const next = item.node;
        const nodeBaseURL = next._baseUrl || item.baseURL;
        const nodeDialect = next._dialect || item.dialect;
        const nodeRecursiveAnchorBase = item.recursiveAnchorBase ?? (next.$recursiveAnchor ? nodeBaseURL : undefined);
        if (seen.has(next)) continue;
        seen.add(next);
        _handleRef(next, nodeBaseURL, nodeDialect, nodeRecursiveAnchorBase, item.inheritedDynamicScope, item.siblingRefCycleKeys);
      }
      return Promise.all(openPromises);
    };

    const resolutionStack = new Set<string>(); // prevents $ref/$recursiveRef/$dynamicRef loops across schema URIs
    const rootResource = schema._baseUrl || schemaURL;
    if (rootResource) resolutionStack.add(rootResource);
    await resolveRefs(schema, schema, schemaURL, dependencies, resolutionStack);
    return new ResolvedSchema(schema, resolveErrors);
  }

  public getSchemaForResource(resource: string, doc: JSONDocument): Promise<ResolvedSchema> {
    const resolveModelineSchema = (): string | undefined => {
      let schemaFromModeline = getSchemaFromModeline(doc);
      if (schemaFromModeline !== undefined) {
        if (!schemaFromModeline.startsWith('file:') && !schemaFromModeline.startsWith('http')) {
          // If path contains a fragment and it is left intact, "#" will be
          // considered part of the filename and converted to "%23" by
          // path.resolve() -> take it out and add back after path.resolve
          let appendix = '';
          if (schemaFromModeline.indexOf('#') > 0) {
            const segments = schemaFromModeline.split('#', 2);
            schemaFromModeline = segments[0];
            appendix = segments[1];
          }
          if (!path.isAbsolute(schemaFromModeline)) {
            const resUri = URI.parse(resource);
            schemaFromModeline = URI.file(path.resolve(path.parse(resUri.fsPath).dir, schemaFromModeline)).toString();
          } else {
            schemaFromModeline = URI.file(schemaFromModeline).toString();
          }
          if (appendix.length > 0) {
            schemaFromModeline += '#' + appendix;
          }
        }
        return schemaFromModeline;
      }
    };

    const resolveSchemaForResource = (schemas: string[]): Promise<ResolvedSchema> => {
      const schemaHandle = super.createCombinedSchema(resource, schemas);
      return schemaHandle.getResolvedSchema().then((schema) => {
        return this.finalizeResolvedSchema(schema, schemaHandle.url, doc, false);
      });
    };

    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    const resolveSchema = async (): Promise<any> => {
      const seen: { [schemaId: string]: boolean } = Object.create(null);
      const schemas: string[] = [];
      let k8sAllSchema: ResolvedSchema = undefined;

      for (const entry of this.filePatternAssociations) {
        if (entry.matchesPattern(resource)) {
          for (const schemaId of entry.getURIs()) {
            if (!seen[schemaId]) {
              if (this.yamlSettings?.kubernetesCRDStoreEnabled && schemaId === KUBERNETES_SCHEMA_URL) {
                if (!k8sAllSchema) {
                  k8sAllSchema = await this.getResolvedSchema(KUBERNETES_SCHEMA_URL);
                }
                const kubeSchema = autoDetectKubernetesSchema(
                  doc,
                  k8sAllSchema,
                  this.yamlSettings.kubernetesCRDStoreUrl ?? CRD_CATALOG_URL
                );
                if (kubeSchema) {
                  schemas.push(kubeSchema);
                  seen[schemaId] = true;
                } else {
                  schemas.push(schemaId);
                  seen[schemaId] = true;
                }
              } else {
                schemas.push(schemaId);
                seen[schemaId] = true;
              }
            }
          }
        }
      }

      if (schemas.length > 0) {
        // Join all schemas with the highest priority.
        const highestPrioSchemas = this.highestPrioritySchemas(schemas);
        return resolveSchemaForResource(highestPrioSchemas);
      }

      return Promise.resolve(null);
    };
    const modelineSchema = resolveModelineSchema();
    if (modelineSchema) {
      return resolveSchemaForResource([modelineSchema]);
    }

    if (this.customSchemaProvider) {
      return this.customSchemaProvider(resource)
        .then((schemaUri) => {
          if (Array.isArray(schemaUri)) {
            if (schemaUri.length === 0) {
              return resolveSchema();
            }
            return Promise.all(
              schemaUri.map((schemaUri) => {
                return this.resolveCustomSchema(schemaUri, doc);
              })
            ).then(
              (schemas) => {
                return {
                  errors: [],
                  schema: {
                    allOf: schemas.map((schemaObj) => {
                      return schemaObj.schema;
                    }),
                  },
                };
              },
              () => {
                return resolveSchema();
              }
            );
          }

          if (!schemaUri) {
            return resolveSchema();
          }

          return this.resolveCustomSchema(schemaUri, doc);
        })
        .then(
          (schema) => {
            return schema;
          },
          () => {
            return resolveSchema();
          }
        );
    }
    return resolveSchema();
  }

  private finalizeResolvedSchema(
    schema: ResolvedSchema,
    schemaUrl: string,
    doc: JSONDocument,
    includeErrorsForSequence: boolean
  ): ResolvedSchema {
    if (schema.schema && typeof schema.schema === 'object') {
      schema.schema.url = schemaUrl;
      if (schema.schema.schemaSequence && schema.schema.schemaSequence[(<SingleYAMLDocument>doc).currentDocIndex]) {
        const selectedSchema = schema.schema.schemaSequence[(<SingleYAMLDocument>doc).currentDocIndex];
        if (includeErrorsForSequence) {
          return new ResolvedSchema(selectedSchema, schema.errors);
        }
        return new ResolvedSchema(selectedSchema);
      }
    }
    return schema;
  }

  // Set the priority of a schema in the schema service
  public addSchemaPriority(uri: string, priority: number): void {
    let currSchemaArray = this.schemaPriorityMapping.get(uri);
    if (currSchemaArray) {
      currSchemaArray = currSchemaArray.add(priority);
      this.schemaPriorityMapping.set(uri, currSchemaArray);
    } else {
      this.schemaPriorityMapping.set(uri, new Set<SchemaPriority>().add(priority));
    }
  }

  /**
   * Search through all the schemas and find the ones with the highest priority
   */
  private highestPrioritySchemas(schemas: string[]): string[] {
    let highestPrio = 0;
    const priorityMapping = new Map<SchemaPriority, string[]>();
    schemas.forEach((schema) => {
      // If the schema does not have a priority then give it a default one of [0]
      const priority = this.schemaPriorityMapping.get(schema) || [0];
      priority.forEach((prio) => {
        if (prio > highestPrio) {
          highestPrio = prio;
        }

        // Build up a mapping of priority to schemas so that we can easily get the highest priority schemas easier
        let currPriorityArray = priorityMapping.get(prio);
        if (currPriorityArray) {
          currPriorityArray = (currPriorityArray as string[]).concat(schema);
          priorityMapping.set(prio, currPriorityArray);
        } else {
          priorityMapping.set(prio, [schema]);
        }
      });
    });
    return priorityMapping.get(highestPrio) || [];
  }

  private async resolveCustomSchema(schemaUri, doc): ResolvedSchema {
    const unresolvedSchema = await this.loadSchema(schemaUri);
    const schema = await this.resolveSchemaContent(unresolvedSchema, schemaUri, []);
    return this.finalizeResolvedSchema(schema, schemaUri, doc, true);
  }

  /**
   * Save a schema with schema ID and schema content.
   * Overrides previous schemas set for that schema ID.
   */
  public async saveSchema(schemaId: string, schemaContent: JSONSchema): Promise<void> {
    const id = this.normalizeId(schemaId);
    this.getOrAddSchemaHandle(id, schemaContent);
    this.schemaPriorityMapping.set(id, new Set<SchemaPriority>().add(SchemaPriority.Settings));
    return Promise.resolve(undefined);
  }

  /**
   * Delete schemas on specific path
   */
  public async deleteSchemas(deletions: SchemaDeletionsAll): Promise<void> {
    deletions.schemas.forEach((s) => {
      this.deleteSchema(s);
    });
    return Promise.resolve(undefined);
  }
  /**
   * Delete a schema with schema ID.
   */
  public async deleteSchema(schemaId: string): Promise<void> {
    const id = this.normalizeId(schemaId);
    if (this.schemasById[id]) {
      delete this.schemasById[id];
    }
    this.schemaPriorityMapping.delete(id);
    return Promise.resolve(undefined);
  }

  /**
   * Add content to a specified schema at a specified path
   */
  public async addContent(additions: SchemaAdditions): Promise<void> {
    const schema = await this.getResolvedSchema(additions.schema);
    if (schema) {
      const resolvedSchemaLocation = this.resolveJSONSchemaToSection(schema.schema, additions.path);

      if (typeof resolvedSchemaLocation === 'object') {
        resolvedSchemaLocation[additions.key] = additions.content;
      }
      await this.saveSchema(additions.schema, schema.schema);
    }
  }

  /**
   * Delete content in a specified schema at a specified path
   */
  public async deleteContent(deletions: SchemaDeletions): Promise<void> {
    const schema = await this.getResolvedSchema(deletions.schema);
    if (schema) {
      const resolvedSchemaLocation = this.resolveJSONSchemaToSection(schema.schema, deletions.path);

      if (typeof resolvedSchemaLocation === 'object') {
        delete resolvedSchemaLocation[deletions.key];
      }
      await this.saveSchema(deletions.schema, schema.schema);
    }
  }

  /**
   * Take a JSON Schema and the path that you would like to get to
   * @returns the JSON Schema resolved at that specific path
   */
  private resolveJSONSchemaToSection(schema: JSONSchema, paths: string): JSONSchema {
    const splitPathway = paths.split('/');
    let resolvedSchemaLocation = schema;
    for (const path of splitPathway) {
      if (path === '') {
        continue;
      }
      this.resolveNext(resolvedSchemaLocation, path);
      resolvedSchemaLocation = resolvedSchemaLocation[path];
    }
    return resolvedSchemaLocation;
  }

  /**
   * Resolve the next Object if they have compatible types
   * @param object a location in the JSON Schema
   * @param token the next token that you want to search for
   */
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  private resolveNext(object: any, token: any): void {
    // eslint-disable-next-line @typescript-eslint/no-explicit-any
    if (Array.isArray(object) && isNaN(token)) {
      throw new Error('Expected a number after the array object');
    } else if (typeof object === 'object' && typeof token !== 'string') {
      throw new Error('Expected a string after the object');
    }
  }

  /**
   * Everything below here is needed because we're importing from vscode-json-languageservice umd and we need
   * to provide a wrapper around the javascript methods we are calling since they have no type
   */

  normalizeId(id: string): string {
    // The parent's `super.normalizeId(id)` isn't visible, so duplicated the code here
    try {
      return URI.parse(id).toString();
    } catch (e) {
      return id;
    }
  }

  getOrAddSchemaHandle(id: string, unresolvedSchemaContent?: JSONSchema): SchemaHandle {
    return super.getOrAddSchemaHandle(id, unresolvedSchemaContent);
  }

  loadSchema(schemaUri: string): Promise<UnresolvedSchema> {
    const requestService = this.requestService;
    return super.loadSchema(schemaUri).then(async (unresolvedJsonSchema: UnresolvedSchema) => {
      // If json-language-server failed to parse the schema, attempt to parse it as YAML instead.
      // If the YAML file starts with %YAML 1.x or contains a comment with a number the schema will
      // contain a number instead of being undefined, so we need to check for that too.
      if (
        unresolvedJsonSchema.errors &&
        (unresolvedJsonSchema.schema === undefined || typeof unresolvedJsonSchema.schema === 'number')
      ) {
        return requestService(schemaUri).then(
          (content) => {
            if (!content) {
              const errorMessage = l10n.t(
                "Unable to load schema from '{0}': No content. {1}",
                toDisplayString(schemaUri),
                unresolvedJsonSchema.errors
              );
              return new UnresolvedSchema(<JSONSchema>{}, [errorMessage]);
            }

            try {
              const schemaContent = parse(content);
              return new UnresolvedSchema(schemaContent, []);
            } catch (yamlError) {
              const errorMessage = l10n.t("Unable to parse content from '{0}': {1}.", toDisplayString(schemaUri), yamlError);
              return new UnresolvedSchema(<JSONSchema>{}, [errorMessage]);
            }
          },
          // eslint-disable-next-line @typescript-eslint/no-explicit-any
          (error: any) => {
            let errorMessage = error.toString();
            const errorSplit = error.toString().split('Error: ');
            if (errorSplit.length > 1) {
              // more concise error message, URL and context are attached by caller anyways
              errorMessage = errorSplit[1];
            }
            return new UnresolvedSchema(<JSONSchema>{}, [errorMessage]);
          }
        );
      }
      unresolvedJsonSchema.uri = schemaUri;
      if (this.schemaUriToNameAndDescription.has(schemaUri)) {
        const { name, description, versions } = this.schemaUriToNameAndDescription.get(schemaUri);
        unresolvedJsonSchema.schema.title = name ?? unresolvedJsonSchema.schema.title;
        unresolvedJsonSchema.schema.description = description ?? unresolvedJsonSchema.schema.description;
        unresolvedJsonSchema.schema.versions = versions ?? unresolvedJsonSchema.schema.versions;
      } else if (unresolvedJsonSchema.errors && unresolvedJsonSchema.errors.length > 0) {
        let errorMessage: string = unresolvedJsonSchema.errors[0];
        if (errorMessage.toLowerCase().indexOf('load') !== -1) {
          errorMessage = l10n.t("Unable to load schema from '{0}': No content.", toDisplayString(schemaUri));
        } else if (errorMessage.toLowerCase().indexOf('parse') !== -1) {
          const content = await requestService(schemaUri);
          const jsonErrors: Json.ParseError[] = [];
          const schemaContent = Json.parse(content, jsonErrors);
          if (jsonErrors.length && schemaContent) {
            const { offset } = jsonErrors[0];
            const { line, column } = getLineAndColumnFromOffset(content, offset);
            errorMessage = l10n.t(
              "Unable to parse content from '{0}': Parse error at line: {1} column: {2}",
              toDisplayString(schemaUri),
              line,
              column
            );
          }
        }
        return new UnresolvedSchema(<JSONSchema>{}, [errorMessage]);
      }
      return unresolvedJsonSchema;
    });
  }

  registerExternalSchema(
    uri: string,
    filePatterns?: string[],
    unresolvedSchema?: JSONSchema,
    name?: string,
    description?: string,
    versions?: SchemaVersions
  ): SchemaHandle {
    if (name || description) {
      this.schemaUriToNameAndDescription.set(uri, { name, description, versions });
    }
    return super.registerExternalSchema(uri, filePatterns, unresolvedSchema);
  }

  clearExternalSchemas(): void {
    super.clearExternalSchemas();
  }

  setSchemaContributions(schemaContributions: ISchemaContributions): void {
    super.setSchemaContributions(schemaContributions);
  }

  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  getRegisteredSchemaIds(filter?: (scheme: any) => boolean): string[] {
    return super.getRegisteredSchemaIds(filter);
  }

  getResolvedSchema(schemaId: string): Promise<ResolvedSchema> {
    return super.getResolvedSchema(schemaId);
  }

  onResourceChange(uri: string): boolean {
    return super.onResourceChange(uri);
  }
}

function toDisplayString(url: string): string {
  try {
    const uri = URI.parse(url);
    if (uri.scheme === 'file') {
      return uri.fsPath;
    }
  } catch (e) {
    // ignore
  }
  return url;
}

function getLineAndColumnFromOffset(text: string, offset: number): { line: number; column: number } {
  const lines = text.slice(0, offset).split(/\r?\n/);
  const line = lines.length; // 1-based line number
  const column = lines[lines.length - 1].length + 1; // 1-based column number
  return { line, column };
}

function normalizeSchemaUri(uri: string | AnySchemaObject): string {
  if (!uri) return '';

  let s: string;
  if (typeof uri === 'string') {
    s = uri;
  } else {
    s = uri.$id || uri.id || '';
  }
  s = s.trim();

  // strips fragment (# or #/something)
  const hash = s.indexOf('#');

  s = hash === -1 ? s : s.slice(0, hash);

  // normalize http to https (don't normalize custom dialects)
  s = s.replace(/^http:\/\/json-schema\.org\//i, 'https://json-schema.org/');

  // normalize to no trailing slash
  s = s.replace(/\/+$/g, '');
  return s;
}

function knownDialectFromSchemaUri(schemaUri?: string): SchemaDialect {
  if (schemaUri === normalizeSchemaUri(ajv4.defaultMeta())) return SchemaDialect.draft04;
  if (schemaUri === normalizeSchemaUri(ajv7.defaultMeta())) return SchemaDialect.draft07;
  if (schemaUri === normalizeSchemaUri(ajv2019.defaultMeta())) return SchemaDialect.draft2019;
  if (schemaUri === normalizeSchemaUri(ajv2020.defaultMeta())) return SchemaDialect.draft2020;
  return undefined;
}

async function pickSchemaDialect(
  $schema: string | undefined,
  loadSchema?: (uri: string) => Promise<UnresolvedSchema>
): Promise<SchemaDialect> {
  if (!$schema) return undefined;
  const s = normalizeSchemaUri($schema || '');

  const dialect = knownDialectFromSchemaUri(s);
  if (dialect) return dialect;

  // cache custom dialect result
  const cached = schemaDialectCache.get(s);
  if (cached) {
    return cached;
  }
  const inflight = schemaDialectInFlight.get(s);
  if (inflight) {
    return inflight;
  }

  if (!loadSchema) return undefined;

  // resolve custom dialect: load the dialect meta-schema doc and infer base dialect from its $schema
  const promise = (async () => {
    const meta = await loadSchema(s);
    if (meta.errors?.length) return undefined;
    const metaSchema = meta.schema;
    if (!metaSchema || typeof metaSchema !== 'object') return undefined;
    const metaDialect = knownDialectFromSchemaUri(metaSchema.$schema);
    if (metaDialect) return metaDialect;
    return undefined;
  })();

  schemaDialectInFlight.set(s, promise);
  try {
    const result = await promise;
    schemaDialectCache.set(s, result);
    return result;
  } finally {
    schemaDialectInFlight.delete(s);
  }
}

function pickMetaValidator(dialect: SchemaDialect): ValidateFunction | undefined {
  switch (dialect) {
    case SchemaDialect.draft04:
      return schema04Validator;
    case SchemaDialect.draft07:
      return schema07Validator;
    case SchemaDialect.draft2019:
      return schema2019Validator;
    case SchemaDialect.draft2020:
      return schema2020Validator;
    default:
      // don't meta-validate unknown schema URI
      return undefined;
  }
}